Pharmacological profiles of the GABA and acetylcholine receptors from the nematode, Ascaris suum.

The pharmacological profiles of the acetylcholine and GABA receptors of Ascaris muscle have been investigated. Acetylcholine excites the muscle through activation of a nicotinic receptor which resembles the mammalian ganglionic receptor. DMPP is a potent agonist and alpha-bungarotoxin is a weak antagonist. GABA inhibits the muscle through activation of a chloride-linked receptor which in terms of agonist profile resembles the mammalian GABA-A receptor. However, bicuculline is inactive and picrotoxin is a very weak antagonist. Avermectin acts as a non-competitive antagonist at this GABA receptor with an IC-50 value in the low microM range.